package com.itheima.utils;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.List;

import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import org.springframework.web.multipart.MultipartFile;

public class POIUtils {
   private final static String xls = "xls";
   private final static String xlsx = "xlsx";
   private final static String DATE_FORMAT = "yyyy/MM/dd";

   /**
    * 读入excel文件，解析后返回
    *
    * @param file
    * @throws IOException
    */
   public static List<String[]> readExcel(MultipartFile file) throws IOException {
      //检查文件
      checkFile(file);
      //获得Workbook工作薄对象
      Workbook workbook = getWorkBook(file);
      //创建返回对象，把每行中的值作为一个数组，所有行作为一个集合返回
      List<String[]> list = new ArrayList<String[]>();
      if (workbook != null) {
         for (int sheetNum = 0; sheetNum < workbook.getNumberOfSheets(); sheetNum++) {
            //获得当前sheet工作表
            Sheet sheet = workbook.getSheetAt(sheetNum);
            if (sheet == null) {
               continue;
            }
            //获得当前sheet的开始行
            int firstRowNum = sheet.getFirstRowNum();
            //获得当前sheet的结束行
            int lastRowNum = sheet.getLastRowNum();
            //循环除了第一行的所有行
            for (int rowNum = firstRowNum + 1; rowNum <= lastRowNum; rowNum++) {
               //获得当前行
               Row row = sheet.getRow(rowNum);
               if (row == null) {
                  continue;
               }
               //获得当前行的开始列
               int firstCellNum = row.getFirstCellNum();
               //获得当前行的列数
               int lastCellNum = row.getPhysicalNumberOfCells();
               String[] cells = new String[row.getPhysicalNumberOfCells()];
               //循环当前行
               for (int cellNum = firstCellNum; cellNum < lastCellNum; cellNum++) {
                  Cell cell = row.getCell(cellNum);
                  cells[cellNum] = getCellValue(cell);
               }
               list.add(cells);
            }
         }
         workbook.close();
      }
      return list;
   }

   //校验文件是否合法
   public static void checkFile(MultipartFile file) throws IOException {
      //判断文件是否存在
      if (null == file) {
         throw new FileNotFoundException("文件不存在！");
      }
      //获得文件名
      String fileName = file.getOriginalFilename();
      //判断文件是否是excel文件
      if (!fileName.endsWith(xls) && !fileName.endsWith(xlsx)) {
         throw new IOException(fileName + "不是excel文件");
      }
   }

   public static Workbook getWorkBook(MultipartFile file) {
      //获得文件名
      String fileName = file.getOriginalFilename();
      //创建Workbook工作薄对象，表示整个excel
      Workbook workbook = null;
      try {
         //获取excel文件的io流
         InputStream is = file.getInputStream();
         //根据文件后缀名不同(xls和xlsx)获得不同的Workbook实现类对象
         if (fileName.endsWith(xls)) {
            //2003
            workbook = new HSSFWorkbook(is);
         } else if (fileName.endsWith(xlsx)) {
            //2007
            workbook = new XSSFWorkbook(is);
         }
      } catch (IOException e) {
         e.printStackTrace();
      }
      return workbook;
   }

   public static String getCellValue(Cell cell) {
      String cellValue = "";
      if (cell == null) {
         return cellValue;
      }
      //如果当前单元格内容为日期类型，需要特殊处理
      String dataFormatString = cell.getCellStyle().getDataFormatString();
      if (dataFormatString.equals("m/d/yy")) {
         cellValue = new SimpleDateFormat(DATE_FORMAT).format(cell.getDateCellValue());
         return cellValue;
      }
      //把数字当成String来读，避免出现1读成1.0的情况
      if (cell.getCellType() == Cell.CELL_TYPE_NUMERIC) {
         cell.setCellType(Cell.CELL_TYPE_STRING);
      }
      //判断数据的类型
      switch (cell.getCellType()) {
         case Cell.CELL_TYPE_NUMERIC: //数字
            cellValue = String.valueOf(cell.getNumericCellValue());
            break;
         case Cell.CELL_TYPE_STRING: //字符串
            cellValue = String.valueOf(cell.getStringCellValue());
            break;
         case Cell.CELL_TYPE_BOOLEAN: //Boolean
            cellValue = String.valueOf(cell.getBooleanCellValue());
            break;
         case Cell.CELL_TYPE_FORMULA: //公式
            cellValue = String.valueOf(cell.getCellFormula());
            break;
         case Cell.CELL_TYPE_BLANK: //空值
            cellValue = "";
            break;
         case Cell.CELL_TYPE_ERROR: //故障
            cellValue = "非法字符";
            break;
         default:
            cellValue = "未知类型";
            break;
      }
      return cellValue;
   }
}
